Method for making molds for dental inlays and the like.



PATENTED DEC. 3, 1907.

W. H. TAGGART. METHOD FOR MAKING MOLDS FOR DENTAL INLAYS AND THE LIKE.

APPLICATION FILED JULY 12, 1907.

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WILLIAM H. TAGGART, OF CHICAGO, ILLINOIS.

METHOD FOR MAKING MOLDS FOR DENTAL INLAYS AND LHCE.

Specification of Letters Patent. Original application filed January 12.1907. Serial No. 351.917. Divided and this Patented 13.0. 3, 1907.application filed .l'nly 12.1907.

Serial No. 383.482.

To all whom it may concern: Be it known that I a citizen of the UnitedStates, residing at Chicago, in the county of Cook and State ofIllinois, have invented a new and useful Im- PTOXlllOllt in Methods forMaking Molds for Dental Inlays and the Like, of which'the 1 following isa specification.

My mvention relates to a certain new and improved method for makingmolds for dental inlays and the like, and its object is to provide, bycertain novel steps of procedure more fully set forth herein, a methodby which molds for such castings can be made with great accuracy andease. The molds produced by my method are particularly designed for thecasting of dental fillings of the type known as inlay fillings, but theycan obviously be used for certain other types of work of a fine grade,one of theirprincipal fields of usefulness being in the formation ofother types of dental metal work, as, for instance, bridge work and thelike.

In the accompanying drawings are shown the various steps of my method aspracticed in making a single mold, Figure 1 being a perspective Viewshowing a tooth and the manner in which the pattern is made therein;Fig. 2, a perspective view of the pattern removed; Fig. 3, a perspectiveview of the pattern showing the sprue former in positlon; Fig. 4, a Viewshowing the pattern and sprue former with the first layer of investingmaterial placed upon the pattern; Fig. 5, a section through the flaskand the cover therefor, showing the pattern and first layer of investingmaterial in position therein; Fig. 6, a similar view showing the flaskfilled with investing material and the flask cover removed Fig. 7, asimilar view showing the flask inverted and the pattern in the processof being removed or dissipated and Fig. 8, a section through thecompleted mold showing it in position'for the casting operation.

This application is a division of an application filed by me on the 12thday of January, 1907, and allotted Serial No. 351,917, the mattersherein particularly shown and described and claimed being the method formaking the mold, togetherwith the mold itself, the casting process beingmore particularly claimed in the foregoing application.

As the first step in my process, I form a pattern A, which isillustrated in Fig. 1.

, WILLIAM H. TAGGART,

This pattern is of wax or other plastic ma-. I

terial and is made in immediate contact with the surface which thecasting is to I it, so that in making a pattern for a tooth filling itis molded directly in the cavity, the upper surface of the pattern beingobtained by having the patient bring the teeth together so that properarticulation is assured. The waxused is of a grade which is plastic atthe tempera, ture of the body and which is especially pure so that itcan be evaporated and leave hehind no solid residue. After the patternis formed in the cavity, it is in practice chilled by the application ofcool water and is removed from position, it being understood that thecavity is of the form commonly made for inlay fillings either of metalor porcelain, 'i. 0., a cavity without overhangs, so that the patterncan readily be removed without distortion.

After the pattern is removed, a sprue former B having a reduced end I)at one end and a sharp point I) at the other for insertion into thematerial of the pattern, is secured thereto by thrusting the sharpenedend into the face of the pattern, which will be on the outside of thetooth, where a trifling irregularity caused by the removal of the spruewill be of comparatively small consequence... The sprue former is thenused as a handle to support the pattern and the entire pattern iscovered with a primary coating of investing material C. This investingmaterial may be any one of the various dental investing materials on themarket, most of said materials being composed of a mixture of pl asterof paris with some silicious material and with other substances, thecompositions of these investing materials varying as they are made bydifferent manufacturers.

It will be understood by those skilled in the art that the dentalinvestment materials vary in quality, some cracking and shrinking. morethan others, the better grades of investing materials being less subjectto these defects than the poorer grades.

In order to get the best results with my process, the best possible.grade of investing material should be used, but the particularcomposition of the investing material used has no bearing upon mypresent invention, although it is of course possible to select aninvesting material sufficiently poor to produce bad results. In placingthis primary body oi; investing material about the pattern,

the greatest care is used to see that there are no air bubbles betweenthe surface of the investing material and the pattern, and a rial hasbeen placed in position, the reduced end I) of the sprue former B isplaced in a perforation at the center of a cover 1) of a flask 1C. Thecenter of the cover 1) has a projection roughly hemispherical in formand designated in the drawings by d and it is at the center of thisprojection that the sprue former is placed. The flask E is then placedin position upon the cover, the parts then occupying the invertedposition shown in Fig. 5. A secondary body F of investing material isthen poured into the flask around the primary body, so that the flaskisentirely filled with mold material, as shown in Fig. 6. When theinvesting material is poured in in this manner, 'air bubbles arenecessarily formed between the body of mold material and the surfaceswith which it contacts and by first placing the primary burner as shownin Fig. 7, and the mold is heated so as to dissipate the wax pattern,the vapors passing ofi through the hole leaving-an unparted mold of theexact form desired. The mold is then completed and may be placed inposition upon the casting device, metal may be placed in thecrucibleshaped depression G and melted, and the remainder of theoperation set forth in the application above identified may besuccessively performed.

What I claim as new, and desire to secure by Letters Patent, is

1. The process of making patterns for dental inlays and the like, whichconsists in molding plastic material upon the tooth sur-- face to thesize and shape of the desired inlay.

2. The process of making patterns for dental inlays and the like, whichconsists in molding wax upon the tooth surface to the size and shape ofthe desired inlay.

3 The process which consists in making a pattern of a tooth fillingwithin the cavity to e filled and in contact with the surface thereof,removing the pattern from the cavity,-

forming about the pattern a mold provided with a sprue, and melting outthe pattern.

4. The roeess which consists in forming a pattern or a tooth filling,attaching to the pattern a sprue former, supporting the pattern by meansof the sprue former within a flask, and introducing investing materialinto the flask around the pattern.

5. The process which consists in making a pattern of a tooth filling inthe cavity to be filled and in contact with the surface thereof,removing the pattern from the cavity, placing about the pattern aprimary body of mold material, adding a secondary bodyof mold materialoutside the primary body, forming a sprue, and removing the pattern fromthe mold thus formed.

6. The process which consists in making a pattern for a cast toothfilling within the cavity to be filled and in contact with the surfacethereof, from plastic material capable of being changed from its solidcondition,

supporting the pattern upon a sprue former, inclosing the attern in aprimary body of mold material: supporting the pattern and primary bodyof mold material within aflask by means of the s rue former, adding asecondary body of mo d material, removing,

sprue former, surrounding the pattern with a primary body of moldmaterial, supporting the pattern and primary body of mold materialwithin a flask by means of the sprue former, ouring in a secondary bodyof mold materia removing the sprue and volatilizing the wax.

8. The process of making molds for casting dental fillings and the like,which consists in forming a pattern of the desired size and shape,forming a mold about said pattern wit a depression in the mold adaptedto form a crucible forming a sprue hole extending from the depression tothe pattern and then removing the pattern.

9. The process of making molds for casting dental fillings and the like,which consists in forming a pattern by molding plastic material upon thetooth surface to the size and shape of the desired inlay, forming a moldabout said pattern, with a depression in the the flask, in which thesprue former is mounted, said projection forming a depression in themold which is adapted to form a crucible, filling the flask withinvestment material, removing the plate carrying the projection andsprne former and then removing the pattern. i

11. The method of forming patterns. for casting dental inlays, whichconsists in molding plastic material in the cavity to he filled to thesize and shape of the desired inlay and obtaining the lower contour ofthe pattern by cooperation of the plastic material with the cavity wall.

12. The method of forming patterns for 15 WILLIAM H. TAGGART.

In presence of- A. U. TuomEU, R. A. SCHAEFEB.

